The use of brushes to clean teeth is a generally accepted means of maintaining oral hygiene. Consequently, many different styles and types of toothbrushes are either disclosed in the art or available in the market. Different combinations of bristle stiffness, handle design, brush head profile, bristle contour and the like provide varying degrees of cleaning, comfort, and, unfortunately, tooth and gum tissue damage.
It is generally known that toothbrushes with contoured bristle heights, can enhance the performance of a toothbrush. Toothbrushes with sinusoidal or serated bristle height patterns have been used, as well as various stepped and smoothed bristle trimming patterns.
It is also generally known that end-rounding of individual bristles reduces tooth and gum tissue damage by removing the sharp edges which result from the bristle trimming operation. See, for example, Bass, The Optimum Characteristics of Toothbrushes for Personal Oral Hygiene, Dent. Items Interest, Vol 70, pp. 697-718 (1948). Positioning the free ends of the bristles against an orbital grinder is a common and very effective means of achieving end rounding when the free ends of the bristles terminate within a common plane. See, for example, U.S. Pat. No. 3,451,173 to Hazelton, issued Jun. 24, 1969, incorporated herein by reference. Unfortunately, contoured bristle patterns exhibit inferior end rounding when performed on a simple orbital grinder as described in the Hazelton patent. If a bristle grinder is set to end round the tallest bristles, the shorter bristles are not rounded to any significant degree. Conversely, grinder penetration sufficient to end round the shorter bristles damages and distorts the ends and the side wall of the longer bristles.
Complex grinding systems have been developed to attempt to end round bristles after they have been attached to the brush head and trimmed to the desired contour. For example, U.S. Pat. No. 2,227,126 issued to Cook on Dec. 31, 1940, discloses a complex combination of contoured grinding wheels, blades and oscillating motions used in an attempt to end round the tips of bristles which are not within a common plane.
It is also well-known in the brush manufacturing industry, that brushes which contain bristle tuft bundles of varying length can be processed on more than one machine. This has been accomplished by stuffing short bristle tuft bundles, trimming them to height and finishing the tips if desired, followed by incremental stuffing, cutting and finishing steps for each longer tuft bundle size. This procedure is slow, and very costly from a capital investment standpoint since several bristling machines are required on each production line.
U.S. Pat. No. 2,426,328 issued to Wandel et al. on Aug. 26, 1947 discloses a thermal process for end rounding bristles. Unfortunately, the thermal process, especially for a contoured brush pattern is a very random process.
Thickening of the bristle ends or fusion of the bristle ends to one another typically result. Both of these characteristics are undesirable in the finished toothbrush. Means to remove such thickenings or fusions, such as with steel brushes are disclosed. However, such removal techniques tend to produce bristle tufts wherein the tips of the individual bristles are no longer uniformly end rounded.
In the German registered design number 1 931 527 (assigned to E. Steinebrunner and Co. Machine Works) a device is described in which tooth brush bristles of a brush can be cut into different lengths without readjusting the machine. This requires a combination of two serated cutting heads, arranged one on top of the other. Therefore, two special serated cutting heads must be combined in a very specific way for each type of brush. A new type of brush with a different arrangement of high and low parts of the bristling material, requires a relatively tedious change in-the arrangement of the combined serated cutting heads, which is time consuming and can only be performed by expert technicians.
The most common, and cost effective method of processing toothbrushes with bristles of varying heights involves using a means of isolating bristles of a particular height during each processing step. Typically, this is done by way of a template, shield or plow to protect non-isolated bristles while the isolated ones are subjected to a processing step.
German Patent application 1 532 773 (assigned to Gottlieb Ebser) discloses a devise having an elongated deflection template (7h) which is moved down upon the head of a toothbrush, deflecting the bristles it contacts away from the select rows of bristles to be isolated. Thus the isolated bristles could be processed without disturbing the deflected bristles. This patent also describes two catch plates (8i and 8h) which wrap around and hug the outer rows of bristles while they are cut to a specific height. This patent appears to be silent on the use of end rounding.
German patent 3 415 870 (assigned to Anton Zahoransky) discloses a machine for treating the tufts of bristles and brushes such as cutting or smoothing them down. In this process pressure is exerted on the outer ends of the longer tufts of bristles by means of a u-shaped cross-sectional pressure piece. (8). Thus, pushing the longer bristles over and leaving them contained within the u-shaped bristle-retaining pressure piece.
European patent 0 078 569 (assigned to G. B. Boucherie, n.v.) relates to a device for separating rows of brush tufts. The devise utilizes a fork-like separator with two knife-like prongs. The fork is introduced through a parallel motion between the knife and brush so that at least one row of brush tufts can be curved away to the side. Thus, the non-displaced bristles can be processed in a trimming and end rounding operation. Forks of this kind are not new in the toothbrush manufacturing art, U.S. Pat. No. 132, 031 to J. Stone (issued Oct. 8, 1872) describes a toothbrush trimmer which utilizes a forked bristle holder (E) to hold bristles to be treated in a trimming operation in place.
Finally, U.S. Pat. No. 5,143,425 discloses a devise for cutting bristles of a toothbrush to different lengths in different selected areas of a tuff pattern. This device utilizes a shield member which is moved down over the bristles to be isolated. The shield member also comprises a ramp means which helps to push or plow the bristles away from the isolated bristles.
Surprisingly, Applicant has discovered a new and improved toothbrush bristle displacing fork. This fork is particularly suited for toothbrush bristle end finishing operations, e.g., end rounding. Accordingly, it is an object of the present invention to provide a bristle finishing fork for rounding the ends of toothbrush bristles affixed to a head which have been trimmed to different heights.
It is a further object of the invention to provide a device which allows the separation of toothbrush bristles into finely delineated areas for bristle finishing.
It is further an object of the present invention to provide a device for isolating and end rounding bristles affixed to a toothbrush head wherein the bristles are cut to different lengths. This device isolates bristles of a particular length, finishes them and then incrementally isolates and then goes on to finish bristles of other lengths in subsequent incremental operations.
These and other objects will be clear from the following: